In audio/visual equipment, powered subwoofers, the speakers dedicated to creating the low-frequency (bass) audio critical in multichannel movie soundtracks like Dolby Digital 5.1, 7.1, and DTS 5.1, 6.1, and 7.1, as well as music, have become extremely popular. Such a subwoofer typically receives a line-level audio signal from a source unit, such as a receiver, preamplifier, processor, or a combination thereof, and amplifies it with an internal amplifier. As such, these powered subwoofers have an electrical cord that is plugged into a standard household electrical outlet that supplies the internal amplifier with electricity.
Additionally, powered loudspeakers, which operate in a similar fashion as powered subwoofers but use one or more internal amplifiers to power all audio frequencies including the mid-range and higher (treble) pitches, have similar power characteristics although they are not as popular in the consumer market. Collectively, the powered loudspeakers and subwoofers are referred to as powered speakers or devices.
Problems arise, though, When turning the devices on and off. Ideally, powered speakers should be energized when, and only when, the source unit is also energized. However, more typically, the user is expected to manually turn these devices on and off each time they want to use them. Because this can be burdensome in some situations, the device's settings are typically ignored by users once they are initially set up and the audio output is configured.
As powered speakers or devices are currently configured, they may be manually left on or off. If the device is left on at all times, unnecessary consumption of energy, unwanted ambient noise when the system is not being used, and potential damage to the electrical components within the device may result. Further, leaving the powered speaker on may emit excess heat resulting in discomfort to the user, or diminishing the performance of neighboring equipment. If the device is left off, the device will often be suboptimally used as owners will forget to turn it on.
Certain conventional devices also have an “auto” setting which will power the device upon receiving an audio input and will typically stay on until the input has ceased for a certain length of time. However, because a powered speaker or device requires a few seconds to warm up, it will not be able to reproduce the first few seconds of audio input and, in the case of a short duration sound input (such as a movie sound effect), the device will not reproduce it at all. Conversely, after being turned on by audio input, powered speakers and devices may remain on for a significant and unnecessary length of time, which, again, may lead to unwanted ambient noise, energy consumption and potential damage to the internal circuitry.
Therefore, powered speakers and devices that are immediately energized or de-energized at the same time as the source unit are desired. Since powering the device based on audio input is too late to be completely effective, it would be desirable to coordinate energizing the device with the energizing of the source unit.
U.S. Pat. No. 6,744,150 to Rendic, issued Jun. 1, 2004, discloses an “outlet strip controlled by PC using low voltage powertap.” Specifically, Rendic discloses a 110V AC power strip that will allow electrical current to any individual component plugged into it only upon receiving a 5V electrical input signal from a directing terminal via a low voltage connection such as a USB port. This device, however, is designed to use the low voltage conduits that are typical in computers as the input signal and would not be able to support a relatively high voltage input signal (typically 110V) that would come from a source device such as a stereo. Also, this reference is not designed to be a simple, inexpensive stand-alone device but is instead an external accessory with additional features such as a fuse or a circuit breaker, which would lead to potentially significant additional costs and less free space. Whatever the precise merits of this and other references, it does not achieve or fulfill the purposes of the present invention.
Therefore, a simple, inexpensive module for activating a powered speaker only when the source unit is on is desired. Further, a powered speaker with reduced equipment wear and power consumption is desired.